SNLS454A November 2014 – March 2019 DS90UB947-Q1
In Forward Channel SPI operation, the SPI master located at the Serializer generates the SPI Clock (SPLK), Master Out / Slave In data (MOSI), and active low Slave Select (SS). The Serializer oversamples the SPI signals directly using the video pixel clock. The three sampled values for SPLK, MOSI, and SS are each sent on data bits in the forward channel frame. At the Deserializer, the SPI signals are regenerated using the pixel clock. In order to preserve setup and hold time, the Deserializer will hold MOSI data while the SPLK signal is high. In addition, it delays SPLK by one pixel clock relative to the MOSI data, increasing setup by one pixel clock.